Sea ice conditions in the Antarctic affect the life cycle of the emperor penguin
(Aptenodytes forsteri). We present a population projection for the emperor penguin population of Terre Adelie, Antarctica, by linking demographic models (stage-structured, seasonal, nonlinear, two-sex matrix population models) to sea ice forecasts
from an ensemble of IPCC climate models. Based on maximum likelihood capture-mark-recapture analysis, we find that seasonal sea ice concentration anomalies (SICa)
affect adult survival and breeding success. Demographic models show that both deterministic and stochastic population growth rates are maximized at intermediate values
of annual SICa, because neither the complete absence of sea ice, nor heavy and persistent sea ice, would provide satisfactory conditions for the emperor penguin. We
show that under some conditions the stochastic growth rate is positively affected by
the variance in SICa. We identify an ensemble of 5 general circulation climate models
whose output closely matches the historical record of sea ice concentration in Terre
Adelie. The output of this ensemble is used to produce stochastic forecasts of SICa,
which in turn drive the population model. Uncertainty is included by incorporating
multiple climate models and by a parametric bootstrap procedure that includes parameter uncertainty due to both model selection and estimation error. The median of
these simulations predicts a decline of the Terre Adelie emperor penguin population
of 81% by the year 2100. We find a 43% chance of an even greater decline, of 90%
or more. The uncertainty in population projections reflects large differences among
climate models in their forecasts of future sea ice conditions. One such model predicts
population increases over much of the century, but overall, the ensemble of models
predicts that population declines are far more likely than population increases. We
conclude that climate change is a significant risk for the emperor penguin. Our analytical approach, in which demographic models are linked to IPCC climate models, is
powerful and generally applicable to other species and systems.

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MH acknowledges support through
the National Science Foundation. HC acknowledges support from NSF Grant DEB-0816514,
from the WHOI Arctic Research Initiative, and from the Alexander von Humboldt Foundation.

The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate ...

This review focuses on the impacts of climate change on population dynamics.
I introduce the MUP (Measuring, Understanding and Predicting) approach, which
provides a general framework where an enhanced understanding of ...